The present invention relates to electrical machines and more particularly to those having a stator, an outer rotor and an inner rotor fastened to the outer rotor.
A machine with two concentric rotors is described in International Application WO 91/06147. The stator has teeth provided at their ends with pole shoes. The coils have heads onto which a heat-transfer fluid, such as oil, is sprayed so as to remove the heat from the windings. Such a machine is relatively complicated to manufacture.
The electric motor described in Application WO 91/06147 is also relatively long in the axial direction, especially because of the coil heads and the means of cooling them.